Enhancement of CO₂ Mineralization in Ca²⁺-/Mg²⁺-Rich Aqueous Solutions Using Insoluble Amine

Abstract

The potential for using concentrated seawater to fix CO2 by adding insoluble amine extractant was tested and verified. The experimental results showed that over 90% of Ca2+ ions could be converted to precipitation. Ammonia was chosen as regenerant to regenerate the extracting agent; the regeneration rate can reach 95%. On the basis of the analysis of MgCO3 precipitation properties, a new CO2 mineralization process was proposed in which CaO is employed to react with Mg2+ in solution. Mg(OH)2 precipitation and Ca2+-rich aqueous solutions were produced, and both performed well in CO2 mineralization. This new process can produce different kinds of byproducts such as MgCO3, CaCO3, and NH4Cl. Since there is no energy consumption from phase separation, nor is there a heat requirement, it is therefore definitely less energy intensive. This approach has great application potential.

Experimental Study of CO2 Mineralization in Ca2+-Rich Aqueous Solutions Using Tributylamine as an Enhancing Medium

“…Reaction 1 is a type of acid−base neutralization, which is exothermic, and our previous work proved that the mineralization reaction was also exothermic. 28 Accordingly, the increase of the temperature reduced the extent of the above exothermic reactions and, therefore, lowered the pH and the mineralization ratio.…”

An Integrated Absorption–Mineralization Process for CO2 Capture and Sequestration: Reaction Mechanism, Recycling Stability, and Energy Evaluation

“…30−33 The integrated absorption−mineralization (IAM) process couples the amine scrubbing process with mineralization, which takes advantage of the fast CO 2 absorption by amine solvents and low energy consumption of CO 2 sequestration. 34,35 The IAM process could convert CO 2 into stable carbonate solids to achieve fast and energy-saving CO 2 sequestration. 36−39 However, the problems restricting IAM lied in the stability of amine solvents and the high cost of calcium sources.…”

“…The integrated absorption–mineralization (IAM) process couples the amine scrubbing process with mineralization, which takes advantage of the fast CO 2 absorption by amine solvents and low energy consumption of CO 2 sequestration. , The IAM process could convert CO 2 into stable carbonate solids to achieve fast and energy-saving CO 2 sequestration. − However, the problems restricting IAM lied in the stability of amine solvents and the high cost of calcium sources. Kang et al figured out that the 2-amine-2-methyl-1-propanol solution regenerated with calcium chloride failed to be recycled to capture CO 2 , while calcium oxide could successfully regenerate the amines and increase cycling stability .…”

Insight into thermal dissociation of tri‐n‐octylamine hydrochloride: The key to realizing CO2 mineralization with waste calcium/magnesium chloride liquids

“…Among the various CCS methods, mineralization by converting CO 2 to carbonate minerals offers an attractive approach for the safe storage and effective utilization of CO 2 . Some Mg 2+ /Ca 2+ —rich aqueous resources, such as seawater, salt lake brines, and industrial effluents have potential application in mineralization of CO 2 .…”